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G. Schütz:
"Single Molecule Biology - Studying Movements and Meetings within the Plasma Membrane";
Vortrag: Seminartalk, Kopenhagen Universität, Kopenhagen/Dänemark; 11.04.2014.

Current scientific research throughout the natural sciences aims at the exploration of the
Nanocosm
, the
collectivity of structures with dimensions between 1 and 100nm. In the life sciences, the diversity of this
Nanocosm attracts more and more researchers to the emerging field of Nanobiotechnology. In my lecture, I
will show examples how to obtain insi
ghts into the organization of the cellular Nanocosm by single molecule
experiments. Our primary goal is an understanding of the role of such structures for immune recognition. For
this, we apply single molecule tracking to resolve the plasma membrane struc
ture at sub
-
diffraction
-
limited
length
-
scales by employing the high precision for localizing biomolecules of ~15nm. Brightness and single
molecule colocalization analysis allows us to study stable or transient molecular associations
in vivo
(
1
). In
particu
lar, I will present results on the interaction between antigen
-
loaded MHC and the T cell receptor
directly in the interface region of a T cell with a mimicry of an antigen
-
presenting cell (
2, 3
).
Moreover, we developed a method for
in vivo
micropatterning
of plasma membrane proteins to measure
molecular interactions
(
4
).
This technology brings together our interest in immune signaling, and the
capability for ultra
-
sensitive readout of large biochip surfaces. C
ells transfected with a fluorescent fusion
prot
ein
("prey")
are
grown
on micropatterned surfaces functionalized with specific antibodies to the
extracellular domain of
a membrane protein ("bait")
; the fluorescence copatterning is used as readout for the
bait
-
prey
interaction.
We applied this technology
for the study of the interaction between CD4
-
the major
coreceptor for T cell activation
-
and Lck, an important tyrosine kinase in early T cell signaling. In addition
to the well
-
known zinc
-
clasp structure, we found strong contributions of Lck membrane
anchorage to the
binding of the two proteins.